Allyson and Oliver have researched destinations and costs for a class trip. The Great Adventure theme park's entry fee is $15 plus they charge $1.50 at each ride using a Fast Pass. The Big Thicket amusement park charges $25 for its entry fee and $1.00 for each ride using a Fast Pass. To be able to ride all the rides, each student will need a Fast Pass for the day. How many ride tickets must be purchased with the Fast Pass in order for the total cost at The Great Adventure theme park and The Big Thicket amusement park to be the same?